Solid State Ionics, Vol.179, No.21-26, 985-990, 2008
Heavily doped oxygen-ion conducting Ln(2+x)Ti(2-x)O(7-delta) (Ln = Ho-Lu; x=0.44-0.81) pyrochlores: Crystal structure, microstructure and electrical conductivity
There are at least two conductivity maxima in the Ln(2)O(3)-TiO2 (Ln = Ho-Lu) systems. High oxide-ion conductivity is typically offered by stoichionnetric or near-stoichiometric Ln(2+x)Ti(2-x)O(7-delta) (Ln = Ho-Lu; x=0-0.096) pyrochlores and heavily doped, disordered Ho-2 (+) Ti-x(2) (-) O-x(7) (-) (delta) (0.48 <= x <= 0.67) pyrochlores just near the boundary of the continuous P --> F phase transition. The conductivity of the fluorite-like Ln(2 + x)Ti(2 - x)O(7 - delta) (Ln = Er-Lu; 0.63-0.74) solid solutions is lower than that of the Ln(2 + x)Ti(2 - x)O(7 - delta) (Ln = Er-Lu; x=0-0.096) pyrochlores, similar to what was reported for the Y2O3-TiO2 System. (C) 2008 Elsevier B.V. All rights reserved.